Angular impact fluid energy mill

ABSTRACT

A fluid energy mill having an inlet chamber, a classification chamber, and an upstack and downstack connecting opposite ends of the inlet chamber to the classification chamber. The inlet chamber, which is positioned angularly to the upstack and downstack, has a Venturi portion between the upstack and downstack. A feed inlet is also positioned angularly to the upstack as well as to the inlet chamber. This feed inlet also has a Venturi portion. A feed hopper is provided above the feed inlet and is in connection therewith. A pressure fluid nozzle is provided below the hopper to project the fluid and particles from the hopper through the Venturi in the feed inlet. A similar but opposed nozzle is provided below the downstack to project fluid through the Venturi in the inlet chamber toward the upstack. The fluid and particles propelled by each nozzle meet and impact below the upstack and the resultant fluid and particles pass upwardly through the upstack and centrifugally move through the mill where the lighter particles are centrifugally separated from the heavier particles and exhausted from the mill.

United States Patent Stephanoff [54] ANGULAR IMPACT FLUID ENERGY MILL [72] Inventor: Nicholas N. Stephanoff, Haverford, Pa.

[73] Assignee: Hewlett-Packard Company, Palo Alto,

Calif.

22 Filed: un is, 1970 211 Appl.No.: 47,357

Primary Examiner-Granville Y. Custer, .lr. Attorney-Arthur A. Jacobs [151 3,675,858 51 July 11,1972

[57] ABSTRACT A fluid energy mill having an inlet chamber, a classification chamber, and an upstack and downstack connecting opposite ends of the inlet chamber to the classification chamber. The inlet chamber, which is positioned angularly to the upstack and downstack, has a Venturi portion between the upstack and downstack. A feed inlet is also positioned angularly to the upstack as well as to the inlet chamber. This feed inlet also has a Venturi portion. A feed hopper is provided above the feed inlet and is in connection therewith. A pressure fluid nozzle is provided below the hopper to project the fluid and particles from the hopper through the Venturi in the feed inlet. A similar but opposed nozzle is provided below the downstack to project fluid through the Venturi in the inlet chamber toward the upstack. The fluid and particles propelled by each nozzle meet and impact below the upstack and the resultant fluid and particles pass upwardly through the upstack and centrifugally move through the mill where the lighter particles are centrifugally separated from the heavier particles and exhausted from the mill.

7 Claims, 2 Drawing Figures P'A'TENTEDJUL 11 I972 3.675.858

1 IN VE N TOR N/CHOLA S N. STEPHA NOFF A 7' TOR/V5 Y ANGULAR IMPACT FLUID ENERGY MILL This invention relates to a fluid energy grinding mill, and it particularly relates to an improved fluid energy mill wherein a higher degree of grinding is effected than in ordinary mills of this type while, at the same time, minimum wear on the walls of the mill is achieved.

Fluid energy mills, as such, are now well-known and are in extensive use. Many of these mills comprise a vertically elongated generally arcuate construction including straight, elongated upstack and downstack sections connected at top and bottom by arcuate elbow sections. Nozzles lead into the lower .elbow portion from a source of gaseous fluid under pressure.

These nozzles are tangentially directed relative to the path of flow through the lower elbow, or inlet, section, and some or all of them may be so positioned that the fluid jets issuing therefrom intersect each other. The inlet section is also provided with a feed inlet for the solid pulverulent material being ground or otherwise treated; this feed inlet being so arranged that the feed path intersects the fluid jet streams so that the particles impact and, during a grinding action, pulverize each other while, at the same time, they are circulated through the mill by the tangentially directed fluid stream.

During the aforesaid type of action, the centrifugal force of the circulating particles carries these particles into a classification zone where they are centrifugally separated into smaller and larger particles, the smaller, lighter particles tending to remain on the inner periphery of the circulating stream while the larger, heavier particles tend to remain on the outer periphery. This centrifugal separation is utilized to remove the lighter particles from the mill while recirculating the heavier particles for an additional pass through the treating area. This is achieved by providing an exhaust duct on the inner periphery of the mill adjacent the entrance to the return stack. As the centrifugal action carries the particles past this exhaust duct, the lighter particles on the inner peripheral portion of the stream flow through the exhaust duct and are removed from the mill, while the heavier particles, on the outer peripheral portion of the stream, pass back into the inlet section and, after being intermixed with additional raw material, are again subjected to the action of the fluid jet streams.

One of the problems of the above type of mill has been to obtain a maximum grinding or pulverization of the particles without undue wear on the walls of the mill because of impact thereagainst by the particles. If the acceleration of the particles is decreased so that there is less impact force on the mill walls, there is a proportional loss of impact action of the particles against each other and, therefore, less effective grinding.

It is one object of the present invention to provide a fluid energy mill wherein a high degree of grinding is obtained with a minimum of wear on the walls of the mill.

Another object of the present invention is to provide a mill of the aforesaid type which is simple in construction and which requires a minimum of moving parts.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a sectional view of a mill embodying the present invention.

FIG. 2 is a sectional view of an alternative embodiment of the present invention.

Referring now in greater detail to the various figures of the drawings wherein similar reference characters refer to similar parts, there is shown in FIG. 1 a mill, generally designated 10, having an inclined inlet chamber 12 from which extends an upstack 14. The upstack 14 extends upwardly to merge into one portion of the periphery of a cylindrical chamber 16. The chamber 16 comprises the classification section of the mill and connected to its opposite peripheral portion is the downstack 18 which leads back into the inlet chamber 12.

At the center of the classification chamber 16 are exhaust outlet openings 20, one on each side. These outlet openings preferably meet at a manifold portion (not shown) where the two streams of exhausted particles are combined and then directed in one stream to a collection station.

In the standard type of fluid energy mill, the nozzles for supplying the gaseous fluid under pressure are situated at the bottom of an arcuate inlet section and direct their jets of fluid in a tangential direction, so that the particles fed into the mill are not only impacted against each other but are caused to flow in an arcuate direction by centrifugal force. The fact that the particles impact each other under tangential fluid forces means that these impacts are usually tangential or-glancing blows rather than full headon blows of the type which would cause a greater degree of pulverization. It is also the standard practice in such mills to inject the raw feed tangentially into the inlet chamber where they are entrained by the pressure fluid jets. In such procedure, some of the initial energy of the fed material is lost during the change of direction.

In the present device, the inlet chamber 12, although inclined, is generally straight rather than arcuate, while the raw feed, which is inserted through a hopper 22 connected to the inclined but straight feed inlet line 24. The feed inlet line 24 is inclined in a direction opposite to that of the inlet chamber 12. A nozzle 26, connected to a source of gaseous fluid under pressure (not shown), extends to a position undemeath the hopper 22. This nozzle 26 directs a jet of gaseous fluid, which entrains the particles falling from hopper 22, through the feed inlet line 24. The feed inlet line 24 has a Venturi-shaped passage 28 which accelerates the stream of fluid and particles in a straight line direction.

At the opposite end of the inlet chamber 12 is provided an opposed nozzle 30, connected to a source of fluid under pressure (not shown). This nozzle is directly below the return end of the downstack 18. The inlet chamber 12, itself, is provided with a Venturi-shaped passage, as indicated at 32.

As the particles and fluid are directed through the Venturi passage 28, they impact the particles and fluid directed through the Venturi passage 32. The particles, thereupon, act to pulverize each other. The resultant ground particles pass upwardly through the upstack 14. This upward movement is substantially due to the opposed angularities of the two fluid jet streams which, after impact, generate an upward component force. The inclined opposed Venturi passages also keep the impact chamber clean and prevent accidental reverse flow.

In addition to providing the impact forces and centrifugal energy for the particles, the Venturi passages also perform other functions. In this respect, since a negative pressure or suction is formed at the entrance to the Venturi passage 28, there is provided a suction feed for the raw particles from hopper 22. In the same manner, the suction created at the entrance to the-Venturi passage 32 draws the returning particles into the inlet chamber from the downstack 18.

In operation, as the raw feed from the hopper 22 is drawn down by the suction, it is propelled horizontally to the right (as viewed in FIG. 1). At the same time, the gaseous fluid jet .from nozzle 30 and Venturi passage 32 is propelled against the particles in the area just below the upstack 14, and creates a vortex wherein the particles pulverize each other. Although the impact of the two opposed forces is direct, their angularity nevertheless provides a definite upward component which causes the fluid and particles resulting from the opposed forces to pass up through the upstack 14. When the fluid, and the particles entrained therein, pass into the chamber 16, they have sufficient centrifugal force to whirl around the chamber.

As the fluid and particles whirl around the chamber 16, the heavier particles are centrifugally carried to the outer peripheral portion of the rotational path, while the lighter particles, on the inner peripheral portion, move in a helical direction toward the exhaust outlets 20 and from there through ducts, connected to these outlets, to a collection station. At the same time, the heavier particles pass down into the downstack 18 and are sucked back into the inlet chamber 12 for another pass.

If desired, tangential nozzles 34 may be provided at the bottom of the classification chamber 16. These nozzles are connected to a source of gaseous fluid (not shown), and this fluid is used to increase the rotational acceleration of the fluid and particles coming from the upstack 14.

A further optional feature is the provision of two opposed, lateral nozzles 36 at the junction of inlet chamber 12 and feed inlet line 24. These nozzles 36, connected to a source of gaseous fluid under pressure (not shown), provide a further direct impact of forces which result not only in enhanced grinding but also in an upward component that increases the centrifugal force.

In FIG. 2 there is shown an alternative form of the mill wherein the mill, generally designated 100, includes an inlet chamber 102 having a Venturi portion 104, a feed hopper 106 connected to a Venturi-type feed inlet 108, a pressure fluid nozzle 112 below the hopper 106, and a pressure fluid nozzle below the downstack, all similar to the corresponding parts in the mill of FIG. 1.

The upstack 114, instead of leading into a cylindrical classification chamber, as in FIG. 1, leads into an arcuate classification section 1 16. The classification section 116 then merges into the downstack 118, whereby a generally arcuate housing, enclosing the centrifugal path of the fluid and particles, is provided. An exhaust duct 120 extends from the inner periphery of the mill adjacent the juncture between the classification section 116 and the downstack 118, whereby the lighter particles, which are centrifugally separated from the heavier particles in the section 116, are exhausted to a collection station. Here, too, optional lateral nozzles 122, similar to those shown at 36 in FIG. 1, may be used.

Except for the arcuate, rather than helical, path of the lighter particles in the classification section, the mill of FIG. 2 functions similarly to the mill of FIG. 1.

The gaseous fluid used is a matter of choice depending upon the material being treated and the results desired. The fluid may, for example, be air, steam, an inert gas or vapor, or any other desirable and feasible gas or vapor; the term gaseous fluid being generic to any gas or vapor. The gaseous jets may be ejected from the nozzles under high velocities of the acoustic or super acoustic range, or low velocities, depending on whether a greater or lesser degree of grinding or other desired results are required.

Although this apparatus has been described primarily for grinding or pulverizing, it may also be used for such other purposes as drying, chemical reactions, coating, agglomerating and many other functions, depending on the type of gaseous fluids used, the materials fed into the mill, and the velocities and pressures of the gaseous fluids as they pass into the mill. For example, if a very hot, low pressure gaseous fluid were used, there would be little or no grinding but only a drying of the particles, if wet. Such drying, itself, causes the formation of lighter and heavier particles because it removes adherent liquid which acts as an adhesive between particles of varying sizes. In addition, the gaseous fluid may be of a type to chemically react with the treated material. Or particles of different chemical composition may be simultaneously used whereby, upon impact, they may physically adhere or chemically combine.

The material being treated may be either pulverulent solid material, a liquid slurry or even a liquid wherein the liquid may be broken up into liquid particles by the atomizing effect of high velocity gases, or it may be a combination of such materials.

I claim:

1. A fluid energy mill comprising an inlet chamber, a feed chamber having a feed means in communication therewith, an impact chamber between said inlet chamber and feed chamber, a classification chamber having an exhaust outlet, an upstack portion leading from said impact chamber to said classification chamber, and a downstack portion leading from said classification chamber to said inlet chamber, said downstack portion being in communication with said inlet chamber at a position spaced from said impact chamber longitudinally of said inlet chamber, said inlet chamber and feed chamber being in opposed relationship to each other and being convergently inclined toward said impact chamber. a first fluid inlet means to inject gaseous fluid into said inlet chamber and to propel said fluid longitudinally of said inlet chamber, a second fluid inlet means to inject gaseous fluid into said feed chamber and to propel said fluid and material fed from said feed means longitudinally of said feed chamber, whereby said gaseous fluids and fed material form intersecting streams in said impact chamber, said inlet chamber, feed chamber and upstack all being angularly inclined relative to each other at angles of less than 180, and said upstack being so arranged relative to said inlet chamber and feed chamber that, upon impact of the intersecting streams in said impact chamber, the resultant force from said impact corresponds to the inclination of said upstack.

2. The mill of claim 1 wherein said classification chamber defines an elliptical flow passage, and wherein said exhaust outlet is in the central portion thereof.

3. The mill of claim 1 wherein said classification chamber is arcuate and said exhaust outlet is on the inner wall portion adjacent the junction between the classification chamber and the downstack.

4. A method of treating pulverulent material which comprises propelling at least two opposed gaseous fluid streams, from different sources thereof, at obtuse angles, in a manner to impact said streams against each other in an impact zone forming a common apex for said fluid streams, said impact zone being situated between said opposite sources, at least one of said fluid streams having pulverulent particles entrained therein, said opposed fluid streams being directed at such angles that the resultant fluid stream caused by their impact is directed at an angle less than l relative to said opposed fluid streams, said resultant stream, with particles resulting from the impact entrained therein, being directed into an arcuate centrifugal path to centrifugally separate the lighter particles from the heavier particles and then return the heavier particles to one of said opposed fluid streams.

5. The method of claim 4 wherein at least two fluid streams are directed through corresponding Venturi passages prior to meeting.

6. The method of claim 4 wherein raw particles are fed into at least one said fluid streams by suction resulting from the acceleration of said fluid streams.

7. The mill of claim 1 wherein additional fluid inlet means are in communication with said impact chamber.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION July 11, 1972 Patent No. 3,675,858 Dated Inventor(s) Nicholas N. Stephanoff It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The Assignee, indicated as "Hewlett-Packard company, pale Alto Calif." should read .---Fluid Energy Processing & Equipment (10., Lansdale, Pa.

Signed and sealed this 31st day of October 1972.

(SEAL) Atte st:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR. Attesting, Officer Commissioner of Patents USCOMM-DC 60376-1 69 U5. GOVERNMENT PRINTING OFFICE: I969 O356-334 FORM PO-105O (10-69) 

2. The mill of claim 1 wherein said classification chamber defines an elliptical flow passage, and wherein said exhaust outlet is in the central portion thereof.
 3. The mill of claim 1 wherein said classification chamber is arcuate and said exhaust outlet is on the inner wall portion adjacent the junction between the classification chamber and the downstack.
 4. A method of treating pulverulent material which comprises propelling at least two opposed gaseous fluid streams, from different sources thereof, at obtuse angles, in a manner to impact said streams against each other in an impact zone forming a common apex for said fluid streams, said impact zone being situated between said opposite sources, at least one of said fluid streams having pulverulent particles entrained therein, said opposed fluid streams being directed at such angles that the resultant fluid stream caused by their impact is directed at an angle less than 180* relative to said opposed fluid streams, said resultant stream, with particles resulting from the impact entrained therein, being directed into an arcuate centrifugal path to centrifugally separate the lighter particles from the heavier particles and then return the heavier particles to one of said opposed fluid streams.
 5. The method of claim 4 wherein at least two fluid streams are directed through corresponding Venturi passages prior to meeting.
 6. The method of claim 4 wherein raw particles are fed into at least one said fluid streams by suction resulting from the acceleration of said fluid streams.
 7. The mill of claim 1 wherein additional fluid inlet means are in communication with said impact chamber. 